Year	Percent
1960	41.10285
1961	32.67745
1962	35.81291
1963	35.32491
1964	30.73167
1965	25.94086
1966	34.45126
1967	26.54032
1968	27.42221
1969	25.67417
1970	26.32374
1971	24.46418
1972	27.02349
1973	29.74387
1974	38.93788
1975	38.30872
1976	45.28797
1977	49.00876
1978	37.93308
1979	50.08539
1980	47.70938
1981	46.88688
1982	37.1436
1983	36.75554
1984	34.10256
1985	34.18164
1986	30.48925
1987	33.58513
1988	33.58217
1989	51.45434
1990	53.71843
1991	47.72824
1992	49.66965
1993	53.19086
1994	84.11365
1995	72.58237
1996	68.01522
1997	54.76644
1998	44.63567
1999	45.96231
2000	43.71854
2001	47.39374
2002	51.07955
2003	49.6666
2004	62.93754
2005	67.81332
2006	67.22394
2007	64.84553